The present invention relates to a complex of novel, sulfur-containing antibiotic compounds demonstrating activity against transplanted tumors designated CL-1577A and CL-1577B and their congeners, to pharmaceutically acceptable derivatives thereof, to a process for the production of said compounds, and to a purified isolate of an actinomycete capable of producing these compounds.
More particularly, the process of producing the CL-1577 complex of antibiotic compounds relates to an aerobic fermentation process using a purified isolate of an actinomycete ATCC 39363.